/* * @(#)InflaterInputStream.java 1.37 04/06/11 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.util.zip; import java.io.FilterInputStream; import java.io.InputStream; import java.io.IOException; import java.io.EOFException; /** * This class implements a stream filter for uncompressing data in the * "deflate" compression format. It is also used as the basis for other * decompression filters, such as GZIPInputStream. * * @see Inflater * @version 1.37, 06/11/04 * @author David Connelly */ public class InflaterInputStream extends FilterInputStream { /** * Decompressor for this stream. */ protected Inflater inf; /** * Input buffer for decompression. */ protected byte[] buf; /** * Length of input buffer. */ protected int len; private boolean closed = false; // this flag is set to true after EOF has reached private boolean reachEOF = false; /** * Check to make sure that this stream has not been closed */ private void ensureOpen() throws IOException { if (closed) { throw new IOException("Stream closed"); } } /** * Creates a new input stream with the specified decompressor and * buffer size. * @param in the input stream * @param inf the decompressor ("inflater") * @param size the input buffer size * @exception IllegalArgumentException if size is <= 0 */ public InflaterInputStream(InputStream in, Inflater inf, int size) { super(in); if (in == null || inf == null) { throw new NullPointerException(); } else if (size <= 0) { throw new IllegalArgumentException("buffer size <= 0"); } this.inf = inf; buf = new byte[size]; } /** * Creates a new input stream with the specified decompressor and a * default buffer size. * @param in the input stream * @param inf the decompressor ("inflater") */ public InflaterInputStream(InputStream in, Inflater inf) { this(in, inf, 512); } boolean usesDefaultInflater = false; /** * Creates a new input stream with a default decompressor and buffer size. * @param in the input stream */ public InflaterInputStream(InputStream in) { this(in, new Inflater()); usesDefaultInflater = true; } private byte[] singleByteBuf = new byte[1]; /** * Reads a byte of uncompressed data. This method will block until * enough input is available for decompression. * @return the byte read, or -1 if end of compressed input is reached * @exception IOException if an I/O error has occurred */ public int read() throws IOException { ensureOpen(); return read(singleByteBuf, 0, 1) == -1 ? -1 : singleByteBuf[0] & 0xff; } /** * Reads uncompressed data into an array of bytes. This method will * block until some input can be decompressed. * @param b the buffer into which the data is read * @param off the start offset of the data * @param len the maximum number of bytes read * @return the actual number of bytes read, or -1 if the end of the * compressed input is reached or a preset dictionary is needed * @exception ZipException if a ZIP format error has occurred * @exception IOException if an I/O error has occurred */ public int read(byte[] b, int off, int len) throws IOException { ensureOpen(); if ((off | len | (off + len) | (b.length - (off + len))) < 0) { throw new IndexOutOfBoundsException(); } else if (len == 0) { return 0; } try { int n; while ((n = inf.inflate(b, off, len)) == 0) { if (inf.finished() || inf.needsDictionary()) { reachEOF = true; return -1; } if (inf.needsInput()) { fill(); } } return n; } catch (DataFormatException e) { String s = e.getMessage(); throw new ZipException(s != null ? s : "Invalid ZLIB data format"); } } /** * Returns 0 after EOF has been reached, otherwise always return 1. *
* Programs should not count on this method to return the actual number
* of bytes that could be read without blocking.
*
* @return 1 before EOF and 0 after EOF.
* @exception IOException if an I/O error occurs.
*
*/
public int available() throws IOException {
ensureOpen();
if (reachEOF) {
return 0;
} else {
return 1;
}
}
private byte[] b = new byte[512];
/**
* Skips specified number of bytes of uncompressed data.
* @param n the number of bytes to skip
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error has occurred
* @exception IllegalArgumentException if n < 0
*/
public long skip(long n) throws IOException {
if (n < 0) {
throw new IllegalArgumentException("negative skip length");
}
ensureOpen();
int max = (int)Math.min(n, Integer.MAX_VALUE);
int total = 0;
while (total < max) {
int len = max - total;
if (len > b.length) {
len = b.length;
}
len = read(b, 0, len);
if (len == -1) {
reachEOF = true;
break;
}
total += len;
}
return total;
}
/**
* Closes this input stream and releases any system resources associated
* with the stream.
* @exception IOException if an I/O error has occurred
*/
public void close() throws IOException {
if (!closed) {
if (usesDefaultInflater)
inf.end();
in.close();
closed = true;
}
}
/**
* Fills input buffer with more data to decompress.
* @exception IOException if an I/O error has occurred
*/
protected void fill() throws IOException {
ensureOpen();
len = in.read(buf, 0, buf.length);
if (len == -1) {
throw new EOFException("Unexpected end of ZLIB input stream");
}
inf.setInput(buf, 0, len);
}
/**
* Tests if this input stream supports the mark
and
* reset
methods. The markSupported
* method of InflaterInputStream
returns
* false
.
*
* @return a boolean
indicating if this stream type supports
* the mark
and reset
methods.
* @see java.io.InputStream#mark(int)
* @see java.io.InputStream#reset()
*/
public boolean markSupported() {
return false;
}
/**
* Marks the current position in this input stream.
*
*
The mark
method of InflaterInputStream
* does nothing.
*
* @param readlimit the maximum limit of bytes that can be read before
* the mark position becomes invalid.
* @see java.io.InputStream#reset()
*/
public synchronized void mark(int readlimit) {
}
/**
* Repositions this stream to the position at the time the
* mark
method was last called on this input stream.
*
*
The method reset
for class
* InflaterInputStream
does nothing except throw an
* IOException
.
*
* @exception IOException if this method is invoked.
* @see java.io.InputStream#mark(int)
* @see java.io.IOException
*/
public synchronized void reset() throws IOException {
throw new IOException("mark/reset not supported");
}
}